No induction of p53 phosphorylation and few focus formation of phosphorylated H2AX suggest efficient repair of DNA damage during chronic low-dose-rate irradiation in human cells

Human fibroblast cells obtained from a normal individual and immortalized by introduction of the hTERT gene were irradiated with 0 to 5 Gy of acute high-dose-rate radiation (1.8 Gy/min) or chronic low-dose-rate radiation (0.3 mGy/min) in the G0 phase, and p53 activation was studied. After high-dose-...

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Bibliographic Details
Published in:Journal of radiation research 2004-12, Vol.45 (4), p.521-525
Main Authors: Ishizaki, Kanji, Hayashi, Yuko, Nakamura, Hideaki, Yasui, Yoshihiro, Komatsu, Kenshi, Tachibana, Akira
Format: Article
Language:English
Subjects:
Analysis
Blotting, Western
Cell Line
Cells (Biology)
DNA
DNA Damage
DNA Repair
Dose-Response Relationship, Radiation
Fibroblasts - metabolism
Fibroblasts - radiation effects
Histones - metabolism
Humans
Phosphorylation
Radiation (Physics)
Resting Phase, Cell Cycle
Tumor proteins
Tumor Suppressor Protein p53 - metabolism
X-Rays
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Summary:Human fibroblast cells obtained from a normal individual and immortalized by introduction of the hTERT gene were irradiated with 0 to 5 Gy of acute high-dose-rate radiation (1.8 Gy/min) or chronic low-dose-rate radiation (0.3 mGy/min) in the G0 phase, and p53 activation was studied. After high-dose-rate irradiation, a dose-dependent induction of Ser15 phosphorylation was observed, whereas after low-dose-rate irradiation almost none was observed. Then we analyzed the focus formation of phosphorylated histone H2AX protein, which is closely correlated with the induction of double-strand breaks. High-dose-rate radiation induced a significant number of foci in a dose-dependent manner, whereas, low-dose-rate radiation could induce only a few foci even at the highest dose. These results strongly suggest that DNA damage induced by low-dose-rate radiation such as a double-strand break is efficiently repaired during chronic irradiation.
ISSN:0449-3060
1349-9157
DOI:10.1269/jrr.45.521